“You are willing to spout the Putin line, sign up for his wish list, break up NATO, do whatever he wants to do,” Clinton said. “[Y]ou continue to get help from him because he has a very clear favourite in this race.”

Clinton pointed out that several US intelligence agencies have found evidence that Russia was behind recent hacks of Democratic Party organisations that they allege were meant to influence the outcome of the presidential election.

Trump has so far refused to place the blame with Russia for the hacks.